Treatment of athabasca tar sands froth



y 1967 G. R. CANEVARI ETAL 3,331,765

TREATMENT OF ATHABASCA TAR SANDS FROTH Filed March 19, 1965 OIL l2 mom WATER -w v WATER TAR SAND u FROTH 8 souos T i: {I 6 n WATER C Q souns SAND Gerard P. Conevori Robert A. Fiocco mentors PotenrAflorney United States Patent 3,331,765 TREATMENT OF ATHABASCA TAR SANDS FROTH Gerard P. Canevari, Cranford, and Robert J. Fiocco, Jersey City, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Mar. 19, 1965, Ser. No. 441,271 6 Claims. (Cl. 20811) The present invention is broadly concerned with the recovery of hydrocarbons from tar sands. The invention is more particularly concerned with an improved technique of efliciently removing hydrocarbons such as bitumen, tars and the like from tar sands containing the same, such as Athabasca tar sands. These sands contain bitumen in the range from about 5.0% to 30% by weight, as for example about 15% by weight. The invention is more particularly concerned with an impoved integrated process for the recovery of oil from tar sands wherein in a first or initial stage a substantial amount of the sands are removed by treatment of the sands with water wherein an oil froth is produced. This oil froth in essence comprises an emulsion of oil and water containing an appreciable amount of solids. This froth is treated in a secondary phase or stage with additional water to remove more solids from the emulsion of oil and water. In a tertiary stage the emulsion, containing some solids, is treated with a chemical mixture to break the emulsion so as to secure an oil phase free of water and solids.

In various areas of the world, tar sands exist which contain various types of hydrocarbons, as for example the heavy deposits of Athabasca tar sands existing in Canada. These sands contain tremendous reserves of hydrocarbon constituents. For example, the oil or bitumen in the sands mary vary from about to 211% by weight, generally in the range of about 12% by weight. The gravity of the oil ranges from about 6 to API, generally about 8 API. These sands lie from about 200 to 300 ft. below an overburden and the beds range from about 100 to 400 ft. thick. A typical oil recovered from the sands has an initial boiling point of about 300 F., 1.0% distilled to 430 F., 20.0% distilled to 650 F. and 50.0% distilled to 980 F.

However, the separation of recovery of hydrocarbons from the solids in the past has not been effective to any great extent, due to the deficiencies in operating techniques for the recovery of these hydrocarbons. For example, a relatively small amount of solid fines (from about 2% to 30%, usually about 5%) in the sand greatly retards recovery of the oil utilizing conventional water techniques. Apparently the oil and the solid fines for-m skins which envelop small pockets of 'water often containing finely divided sand; then the enveloped pockets are distributed in the oil, thus forming a water in oil type of emulsion.

Numerous attempts have been made in the past to recover bitumen from the Athabasca tar sands by various techniques. For example, it has been suggested that a solvent be added in order to reduce the viscosity of the bitumen, and in conjunction wit-h water, to float the bitumen solvent mixture away from the sand. Although this technique achieves a good separation of clean sand, the addition of water results in problems with the formation of stable emulsions and sludges which has been very diflicult to separate. Thus, extensive supplementary processing has been required in order to avoid large oil losses.

It has now been discovered that if a chemical mixture be used, particularly in a third stage of a three-stage operation, excellent separation of the solids from the oil is secured. This chemical mixture in essence is demulsifying agents used in combination with transfer agents" and chelating or complexing agents. A very desirable chemical mixture comprises a transfer agent, a chelating agent and a demulsifyin-g agent used in combination with a hydrocarbon solvent.

The process of the present invention may be more fully understood by reference to the drawing illustrating one embodiment of the same. Referring to the drawing, water is introduced into initial stage 1 by means of line 3 and Athabasca tar sands as described by means of line 2. The sand and water are thoroughly agitated and mixed by means of stirrers 4 and 5. Sand is withdrawn from zone 1 by means of line 7, while a froth is removed from zone 1 by means of line 6.

The amount of water used in zone 1 based upon the volume of tar sands may be varied appreciably, as for example, from about 0.5 to 2.0 volumes of water, preferably about 0.8 to 1.2 volumes such as 1 to 1 volume of water per volume of tar sands. Temperatures maintained in zone 1 are in the range from about F. to 200 F, preferably in the range from 170 F. to 190 F. such as about 180 F. Under these conditions, most of the solids, particularly sand, are removed from zone 1 by means of line 7.

Under these conditons, a froth comprising water, nonseparated solids and oil is produced which. is removed from zone 1 by means of line 6. The froth comprises from about 25 to 45% by weight of water, as for example 35% by weight of water, 5 to 25% by weight of solids, as for example about 15% by weight of solids, the remainder being bitumen. This froth is introduced into secondary zone 8 wherein the same is preferably countercurrently contacted with additonal water which is introduced into zone 8 by means of line 9. The amount of water used in zone 8 as compared to the volume of froth is in the range from about 0.5 to 1.5 volumes of water, preferably about 0.8 to 1.2 such as 1 to 1 volume of water per volume of froth. The temperature in zone 8 is maintained in the range from about F. to 200 R, such as about 180 F. By this technique all but about 10% of the solids are removed with the water by means of line 10.

The froth containing from about 5 to 15% of solids, usually about 10% of solids is removed from zone 8 by means of line 11 and introduced into tertiary zone 12. In tertiary zone 12 an additive mixture is introduced by means of line 13. An oil phase substantially completely free of water and solids is removed by means of line 14 while a water phase containing solids is removed by means of line 15. The temperature in zone 12 is maintained in the range from about 120 to 190 F., preferably in the range from about to R, such as 180 F.

The additive mixture introduced by means of line 13 preferably contains from about 0.1 to 2.0%, preferably about 1% by weight based on the froth, of a transfer agent such as tetrasodium pyrophosphate, or sodium tripolyphosphate. Other equivalent chemicals which may be used are for example potassium pyrophosphate, sodium hexametaphosphate and sodium silicate. Thesetransfer agents promote the transfer of the solid fines from the oil/water interface into the aqueous phase by establishing a uniform electropotential over the entire surface of the particle. In general inorganic builders and condensed phosphates act as transfer agents.

A second constituent of the chemical mixture introduced into zone 12 is a demulsifying additive. These demulsifying additives are nonionic surface active compounds, as for example a polyethoxyalkylene compound marketed under the trade name Nalco D4645 produced by the N-alco Chemical Company.

Another preferred demulsifying solution comprises a mixture of: (1) one part of the reaction product of diethyl ethanol amine with premixed propylene oxide and a ethylene oxide. (Propylene oxide/ ethylene oxide can range from 40/60 to 60/40, preferably 55/45.) (2) Approximately three parts of a palmitic acids ester of the reaction product of an alkyl phenol formaldehyde resin with ethylene oxide (alkyl phenol formaldehyde 1 ethylene oxide 1.5

a=molecular weight range of 50 to 7000 b=molecular weight range of 900 to 4000 c=molecular weight range of 50 to 7000 These compounds have molecular weights ranging from about 1000 to over 16,000.

The amount of demulsifier used is in the range fro-m about 0.01 to .5%, for example 0.2% by weight based on the weight of the total emulsion.

In instances where the froth may contain heavy minerals, for example sometimes as high as 2 to by Weight of heavy minerals as for example Zircon, rutile, ilmenite, tourmaline, apatite, staurolite, garnet, etc., it may be desirable to employ chelating agents in addition to a demulsifier and transfer agent. For example, chelating agents which may be used as part of the chemical mixture introduced into zone 12 are ethylenediamine-tetraacetic acid, sodium gluconate, gluconic acid, sodium oxalate and diethylene glycol.

As pointed out heretofore, the chemical mixture may contain a hydrocarbon solvent boiling in the range from about 250 to 600 F., preferably in the range from about 250 to 450 F. Preferred solvents are xylene and naphtha boiling in the range from about 250 to 450 F. The amount of solvent used is in the range from to 100% by weight of the froth, preferably about 50%.

The present invention may be more fully understood by the following example illustrating the same.

Example A froth which had been processed in an initial stage and in a secondary stage as described contained about 8% of solids, including heavy minerals.

Six operations were conducted, Operation 1-3 at room temperature and Operations 4-6 at a temperature of 120 F. In Operations 1 through 6 froth introduced into the tertiary zone was mixed with xylene in a 1 to 1 Weight ratio. In Operations 2 and 5, 1% by weight of froth of sodium pyrophosphate was also introduced into the tertiary zone. In Operations 3 and 6 the mixture introduced into the tertiary zone was similar to that in Operations 2 and 5 except that it also contained about .2% by weight of froth of the preferred demulsifier.

In Operations 1 and 4 very little separation of solids and water occurred. In Operations 2 and 5 substantial amounts of the solids and water were removed, while in Operations 3 and 6 the oil phase which separated was substantially free of solids and water.

What is claimed is:

1. Process for the recovery of bitumen from tar sands which comprises mixing tar sands with water at a temper- =ature in the range from about 140 F. to 200 F. in an initial stage under conditions to segregate sand and a froth consisting of water, solids and bitumen; separating said froth from said initial stage and countercurrently contacting the same in a secondary stage with additional water at a temperature in the range from about 160 F. to 200 F. to remove additional solids from said froth; thereafter passing the same to a tertiary stage and contacting the same in said tertiary stage at a temperature in the range from about F. to 190 F. with a chemical mixture comprising a demulsifying agent, a transfer agent, a chelating agent and a hydrocarbon solvent whereby an oil phase separates which is substantially free of solids.

2. Process as defined by claim 1 wherein said transfer agent is selected from the class of alkali metal condensed phosphates or silicates and wherein said demulsifying additive is a nonionic surface active compound.

3. Process as defined by claim 2 wherein said hydrocarbon solvent boils in the range from about 250 F. to 600 F. and wherein the amount of solvent used is in the range from about 10 to 100% by volume based upon the froth.

4. Process for the recovery of bitumen from tar sands which comprises mixing tar sands with 0.5 to 2.0 volumes of water based upon the tar sands at a temperature in the range from about F. to 200 F. in an initial stage under conditions to segregate sand and a froth; separating said froth from said initial stage and countercurrently contacting the same in a secondary stage with 0.5 to 1.5 volumes of additional Water at a temperature in the range from about F. to 200 F. to remove additional solids from said froth; thereafter passing the froth to a tertiary stage and contacting the same at a temperature in the range from about 120 F. to F. with a chemical mixture comprising (1) from about .01 to .5 weight percent of a demuls-ifying agent, (2) from about .1 to 2% by weight of a transfer agent and (3) about 10 to 100% by volume of a hydrocarbon solvent boiling in the range from about 250 F. to 600 F. whereby an oil phase separates which is substantially free of solids.

5. Process as defined by claim 4 wherein said transfer agent is an alkali metal condensed phosphate such as tetrasodium pyrophosphate.

6. Process as defined by claim 5 wherein said demulsifying agent consists of a demul-sifying agent comprising a mixture of (a) one part of the reaction product of diethyl ethanol amine with premixed propylene oxide and ethylene oxide wherein the ratio of propylene oxide to ethylene oxide ranges from 40/60 to 60/40% by volume and (b) approximately three parts of a palmitic acids ester of the reaction product of an alkyl phenol formaldehyde resin with ethylene oxide, said reaction product having the following ratio,

alkyl phenol formaldehyde 1 ethylene oxide T5 References Cited DANIEL E. WYMAN, Primary Examiner.

P. E. KONOPKA, Assistant Examiner. 

1. PROCESS FOR THE RECOVERY OF BITUMEN FROM TAR SANDS WHICH COMPRISES MIXING TAR SANDS WITH WATER AT A TEMPERATURE IN THE RANGE FROM ABOUT 140*F. TO 200*F. IN AN INITIAL STAGE UNDER CONDITIONS TO SEGREGATE SAND AND A FROTH CONSISTING OF WATER, SOLIDS AND BITUMEN; SEPARATING SAID FROTH FROM SAID INITIAL STAGE AND COUNTERCURRENTLY CONTACTING THE SAME IN A SECONDARY STAGE WITH ADDITIONAL WATER AT A TEMPERATURE IN THE RANGE FROM ABOUT 160*F. TO 200*F. TO REMOVE ADDITIONAL SOLIDS FROM SAID FROTH; THEREAFTER PASSING THE SAME TO A TERTIARY STAGE AND CONTACTING THE SAME IN SAID TERTIARY STAGE AT A TEMPERATURE IN THE RANGE FROM ABOUT 120*F. TO 190*F. WITH A CHEMICAL MIXTURE COMPRISING A DEMULSIFYING AGENT, A TRANSFER AGENT, A CHELATING AGENT AND A HYDROCARBON SOLVENT WHEREBY AN OIL PHASE SEPARATES WHICH IS SUBSTANTIALLY FREE OF SOLIDS. 